JPH09208932A - Expandable rubber composition for packing structure and foam for packing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inexpensive and expandable rubber composition for packing a structure, excellent in storage stability and foam for packing a structure, having excellent compressive rigidity and large energy absorbing amount. SOLUTION: This expandable rubber composition is arranged in a prescribed space in a structure and expanded by being heated to pack the space in the structure with the composition. The rubber composition is obtained by blending 100 pts.wt. diene-based rubber with 10-50 pts.wt. sulfur or 1-30 pts.wt. sulfur, 5-100 pts.wt. rigidity imparting agent and 5-40 pts.wt. foaming agent. This foam for packing a structure is obtained by heating and expanding the expandable rubber composition and has >=0.5kN/mm/25cm<2> area compressive rigidity and >=100kN.mm/25m<2> energy absorption amount.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a foamable rubber composition for filling a structure and a foam for filling a structure, and particularly to a foamable rubber composition for filling a structure which is excellent in storage stability at low cost, and the same. The present invention relates to a structure-filling foam having excellent rigidity, which can be advantageously obtained by heating and foaming such a foamable rubber composition.

[0002]

BACKGROUND ART Generally, a skeleton member (structure) such as a front pillar or a center pillar of an automobile has a cavity, and when wind passes through the cavity, wind noise is generated or The vibration noise of the engine is transmitted to the inside of the vehicle through such a hollow portion, which causes the noise in the vehicle. Therefore, it has been conventional to suppress the passage of wind and the transmission of vibration noise by filling foam in the void portion of the structure such as the skeleton member that causes noise in the vehicle. Measures have been taken to improve sound insulation.

As a method for filling such a void with a foam, a foam formed according to the shape of the void is inserted into the void through a working hole, or foamed by heating to obtain a volume. A method of filling an expanding foamable composition into a sheet shape as a spot sealing material, filling it, arranging it in a void, and foaming it by heating in a baking furnace for electrodeposition coating to fill the void. Etc. various methods are adopted.

However, in the method of inserting the foam into the void, since the foam is inserted through the working hole, the filling property varies, and it is difficult to completely fill the voids along the shape of the void. is there. Moreover, since the work hole is the punched edge of the steel plate, there is a risk that the worker may hurt his hand.

[0005] In recent years, in order to improve the strength of a structure as well as to improve the conventional interior noise,
It is becoming more common to fill foams with structures. As such a foamable composition for filling a structure, a foamable composition made of an epoxy resin is used in order to obtain high rigidity. However, in general, the epoxy resin is high in cost including the crosslinking agent, and the molded sheet of the foamable composition made of such an epoxy resin is in a state after adding a curing agent to the epoxy resin, From the so-called B-stage state, even if it is not heated, the reaction progresses rapidly under the temperature condition of about 40 ° C. due to the water vapor in the atmosphere, and the reaction is automatically (automatically) cured. Therefore, there is a problem that the storage stability is poor. Therefore, the foamable composition made of such an epoxy resin must be stored in a sealed bag filled with silica gel in a cool and dark place, and stored with great care. It was very troublesome.

[0006]

The present invention has been made in view of such circumstances, and a problem to be solved by the present invention is a foam for filling a structure, which is low in cost and excellent in storage stability. Another object of the present invention is to provide a structural rubber composition, and also to provide a foam for filling a structure, which has a high compression rigidity and a large amount of energy absorption.

[0007]

In order to solve such a problem, the present invention provides a foamable rubber which is placed in a predetermined void in a structure, foams when heated, and fills the void in the structure. A foamable rubber for filling a structure, which is a composition comprising 10 to 50 parts by weight of sulfur and 5 to 40 parts by weight of a foaming agent with respect to 100 parts by weight of a diene rubber. The composition is the gist of the invention.

Further, the present invention is a foamable rubber composition which is placed in a predetermined void in a structure and foams when heated to fill the void in the structure, which comprises a diene rubber. 1 to 30 parts by weight of sulfur, 5 to 100 parts by weight of a rigidity-imparting agent, and 5 to 40 parts by weight of a foaming agent are mixed with 100 parts by weight of the foamable rubber for filling a structure. A composition is also included in the gist thereof.

That is, in the foamable rubber composition for filling a structure according to the present invention, a diene rubber is used as a main component, and a predetermined ratio of sulfur, or a predetermined ratio of sulfur and a rigidity-imparting agent is used. Is characterized in that it is compounded for the purpose of increasing the rigidity of the obtained foam. And, since a rubber material composed of a diene rubber is used as a main component, sulfur is used as a cross-linking agent. However, such a rubber material and sulfur are inexpensive and are obtained. The foamable rubber composition for filling the structure can be made inexpensive. Further, the rubber material used in the present invention has excellent storage stability even if it is stored in a state in which sulfur as a cross-linking agent is blended, and does not spontaneously cure unless it is heated. Therefore, it is not necessary to adopt a very troublesome storage method as in the case of the conventional foamable composition using an epoxy resin.

Moreover, since the foam obtained by heating and foaming this expandable rubber composition has the properties of rubber succeedingly, it has excellent toughness due to the elasticity derived from rubber. It has a greater impact energy absorption property than a foam.

When a structure in which a rigidity-imparting agent is used in combination with sulfur as a cross-linking agent is adopted, the rigidity of the foam obtained by heating and foaming the rigidity-imparting agent becomes excellent. Therefore, there is a feature that the amount of added sulfur can be reduced.

The present invention also provides a foamable rubber composition prepared by blending 10 to 50 parts by weight of sulfur and 5 to 40 parts by weight of a foaming agent with 100 parts by weight of a diene rubber as described above. Compressive rigidity of 25c obtained by heating and foaming
The gist of the foam for filling a structure is that it is 0.5 kN / mm or more per m ² , and the energy absorption amount is 100 kN · mm or more per 25 cm ² .

Further, in the present invention, 100 parts by weight of diene rubber is blended with 1 to 30 parts by weight of sulfur, 5 to 100 parts by weight of a rigidity-imparting agent and 5 to 40 parts by weight of a foaming agent. The resulting foamable rubber composition is heated and foamed to obtain a compression rigidity of 0.5 kN / mm or more per 25 cm ² , and an energy absorption amount of 10 per 25 cm ^2.
A foam for filling a structure, which is characterized in that it is 0 kN · mm or more, is also included in the gist of the present invention.

In short, the structure-filling foam according to the present invention as described above can be easily obtained by heating and foaming the structure-filling foamable rubber composition having the above-mentioned excellent properties. , compressive stiffness of such foams is a 25 cm ² per 0.5 kN / mm or higher, and the energy absorption amount is a 25 cm ² per 100 kN · mm or more, have excellent rigidity and large energy absorption Of.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The diene rubber used in the foam for filling structure or the foam for filling structure according to the present invention is a natural rubber (N
R), butadiene rubber (BR), styrene-butadiene rubber (SBR) and the like, any known diene rubber can be used, and a blended product thereof can also be used.
No problem.

Sulfur is added in order to increase the rigidity of the foam obtained by heating and foaming the foamable rubber composition due to the cross-linking effect of sulfur, and the amount used is to impart rigidity. If you can not mix the agent,
In order to increase the rigidity only by crosslinking with sulfur, it is necessary to be blended in a larger amount, whereas, when a stiffening agent is blended, the rigidity is increased only by crosslinking with sulfur. Since it is not necessary, a small amount of the compound is sufficient.

That is, when the rigidity-imparting agent is not compounded, sulfur must be compounded in a ratio of 10 to 50 parts by weight with respect to 100 parts by weight of the diene rubber. This is because if the blending ratio is less than 10 parts by weight, the resulting foam will have an insufficient crosslinking density, resulting in too low rigidity, and if the blending ratio is more than 50 parts by weight. In addition, since the cross-linking density of the obtained foam becomes too large, the foaming of the rubber composition becomes insufficient.

On the other hand, when the rigidity-imparting agent is blended, sulfur is added to 100 parts by weight of the diene rubber.
The mixing ratio is 1 to 30 parts by weight. In this case, if the mixing ratio of sulfur is less than 1 part by weight, the rigidity of the obtained foam is insufficient, and if it is higher than this, the rigidity of the obtained foam becomes too high and It causes problems such as fragility of the body.

The above-mentioned rigidity-imparting agent is added for the purpose of imparting rigidity to a foam obtained by heating and foaming a foamable rubber composition, and by adding this rigidity-imparting agent, The sulfur content can be reduced. Specific examples of such a rigidity imparting agent include thermosetting resins such as phenolic resins, epoxy resins, melamine resins, and urethane resins, and modified products thereof. And the compounding ratio of such a rigidity imparting agent is set to 5 to 100 parts by weight with respect to 100 parts by weight of the diene rubber. This is because, if the blending ratio is less than 5 parts by weight, the effect of the rigidity-imparting agent cannot be fully exerted, and if the blending ratio is more than 100 parts by weight, the resulting foam is obtained. This is because the rigidity of is too high, which is not preferable. In order to further enhance the effect of the rigidity-imparting agent, a curing agent such as hexamine is added to the thermosetting resin at a ratio of about 20 to 30% of the theoretical equimolar amount of the resin. As a result, the rigidity can be increased more advantageously.

Further, the foaming agent used in the present invention decomposes when the rubber composition is heated to release a gas such as carbon dioxide or nitrogen gas so that a foam is formed. , Those which are added and conventionally known ones can be appropriately adopted. Specific examples of such a foaming agent include inorganic ones such as sodium hydrogen carbonate, ammonium carbonate, and ammonium hydrogen carbonate, Examples thereof include diazoamino derivatives, azonitriles, azodicarboxylic acid derivatives, and dinitrosopentamethylenetetramine. Then, this foaming agent is added at a compounding ratio of 5 to 40 parts by weight with respect to 100 parts by weight of the diene rubber. This is because when the blending ratio is less than 5 parts by weight, the sufficient foaming action cannot be exhibited, and when it is more than 40 parts by weight, the further foaming action is not exhibited. Because there is no.

The expandable rubber composition for filling a structure according to the present invention contains, in addition to the above-mentioned diene rubber, sulfur, a rigidity-imparting agent and a foaming agent, various conventionally known compounding agents, for example, Vulcanization accelerators, vulcanization aids, processing aids, fillers, etc. are added as necessary, and any of them is the same as conventional ones in a range not impairing the object of the present invention. It goes without saying that there is no problem in mixing them. For example, a metal oxide such as zinc oxide is used as the vulcanization aid, and is generally mixed in a proportion of about 3 to 15 parts by weight with respect to 100 parts by weight of the diene rubber. In addition, as a processing aid, a fatty acid such as stearic acid is used in an amount of about 0.5 to 5 parts by weight based on 100 parts by weight of the diene rubber. Further, softening agents include liquid rubber, paraffin-based, naphthene-based, aroma-based process oils and ester-based plasticizers.
It is used in a proportion of about 0 to 100 parts by weight with respect to parts by weight, and further, as the filler, calcium carbonate, carbon black, silica, talc, etc. is used as a diene rubber.
It is used in a ratio of about 0 to 150 parts by weight with respect to 00 parts by weight.

The expandable rubber composition for filling a structure according to the present invention comprises a diene rubber material and a predetermined amount of sulfur or a sulfur and a rigidity-imparting agent and a foaming agent, according to a mixing method similar to the conventional one. It is prepared by blending and further blending the above-mentioned various blending agents.

The foam for filling a structure according to the present invention can be easily obtained by heating the foamable rubber composition for filling a structure according to the present invention prepared as described above. That is, when the foamable rubber composition for filling the structure is heated, it easily foams and cures to become a desired foam. Then, at that time, the compression rigidity of the obtained foam for filling the structure is 25c.
The heating conditions are selected so that the energy absorption amount is 0.5 kN / mm or more per m ² and the energy absorption amount is 100 kN · mm or more per 25 cm ² , and foaming and curing are performed. More specifically, generally 160-210 ° C.
It is heated for about 15 to 30 minutes under this temperature condition.

By the way, the compression rigidity as referred to in the present invention means that when a pair of surfaces of a foam test piece formed in a cube with one side of 5 cm is compressed, it is compressed at 20 mm / min in the compression direction. As described above, the compressive load P is applied, the relationship between the displacement amount S at that time and the compressive load P is obtained, and the initial load slight change amount (ΔP) is divided by the initial displacement slight change amount (ΔS). and means a value obtained by, it specimens 25 cm ²
It is represented by the value per hit. Further, the amount of absorbed energy in the present invention means, from the start of compression, when the above-mentioned foam test piece is compressed as described above,
It means the amount of energy absorbed by the test piece until the compressive displacement of the test piece reaches 30 mm, which is expressed by a value per 25 cm ² of the test piece. Specifically, a graph showing the relationship between the displacement amount: S and the compression load: P is shown in FIG. 1. In this graph, the compression rigidity is the displacement amount: S and the compression load: P. Is the initial rising slope (ΔP / ΔS) of the relational curve of, and the absorbed energy amount is the relational curve of the compressive load: P and the displacement amount: S,
The area surrounded by the x-axis (0 to 30 mm) (black-painted portion in FIG. 1).

The large compression rigidity means that
It means that the foam has high rigidity, and that the large amount of energy absorption means that the foam does not easily collapse when the same amount of energy is applied to the foam. .

Therefore, the structure-filling foam according to the present invention is resistant to impact and is not easily crushed. Therefore, when it is applied to a structure such as a skeleton of an automobile, it may cause an automobile accident. Since the shock is advantageously absorbed, the safety of passengers can be effectively improved.

Incidentally, when the foam for filling a structure according to the present invention is actually applied to a structure of an automobile, first,
After the structure foamable rubber composition processed into a sheet is fixedly placed in the internal voids of the structure, it is subjected to normal automobile manufacturing processes such as welding, degreasing / washing, and electrodeposition, and then paint baking. It is not necessary to provide any special heating step since it is foamed and cured by being heated in the steps such as.

[0028]

EXAMPLES In order to clarify the present invention more specifically, representative examples of the present invention will be shown below.
It goes without saying that the present invention is not subject to any restrictions by the description of such embodiments. In addition, in addition to the following examples, the present invention, in addition to the above-described specific description, various changes, corrections, and modifications based on the knowledge of those skilled in the art without departing from the spirit of the present invention. It should be understood that improvements can be made.

First, foamable rubber compositions for filling various structures having the compositions shown in Table 1 below were prepared. In addition to the components shown in Table 1, each composition contains 5 parts by weight of zinc oxide as a vulcanization aid, 1 part by weight of stearic acid as a processing aid, and 20 parts by weight of ground calcium carbonate. , And process oil: 5 parts by weight are blended. As the process oil, a naphthene type process oil was used for the rubber compositions of the present invention examples 1 to 3, and an aroma type process oil was used for the rubber compositions of the present invention example 4 and Comparative examples 1 and 2. No processing oil was added to the rubber composition of Inventive Example 5.

[0030]

[Table 1]

Next, the foamable rubber compositions for filling various structures obtained above are held in a drying oven adjusted to 180 ± 2 ° C. for 20 ± 2 minutes for heating and foaming, respectively. A corresponding foam was obtained. And
The foaming ratio and block physical properties of the obtained foamed product were examined, and the results are shown in Table 2 below. The expansion ratio was also examined under the conditions of 160 ° C. × 20 minutes and 215 ° C. × 20 minutes. Also, the vulcanization speed was investigated. The results are also shown in Table 2 below.

The vulcanization speed was obtained by using a vulcanization curve at 180 ° C. measured by a Monsanto rheometer at a value of 10% torque (T ₁₀ ) of the maximum torque and 90% of the maximum torque.
The value in% torque (T ₉₀ ) was determined.

The expansion ratio of each foamable rubber composition was 200 mm × 300 mm and the thickness was 0.8.
After being formed into a sheet having a size of 100 mm × 100 mm and a thickness of 5 mm on an oil-mm steel plate having a size of 5 mm, heating is performed by holding for a predetermined time in a drying oven adjusted to a predetermined temperature to foam, It was measured by determining the ratio (%) of the maximum sheet thickness after foaming to the sheet thickness before curing after foaming.

Further, the block physical properties are 20 ± 2 in a drying oven in which the foamable rubber composition is adjusted to 180 ± 2 ° C.
By holding for a minute, foaming and curing were performed, and the obtained foamed body was made into a cubic test piece of 50 × 50 × 50 mm. Next, an autograph with a size of 50 × 50 mm or more and a flat steel plate having a sufficient thickness was prepared, and the obtained test piece was used to prepare a pair of surfaces, Compress at a speed of 20 mm / min in the direction perpendicular to the axis, and take the displacement amount at that time on the horizontal axis (x axis),
The compressive load was taken on the vertical axis (y-axis), and their relationship curves were obtained as a graph (see FIG. 1). Then, from the graph, the slope of the rising curve at the initial stage of compression is taken as the value of the compression stiffness, and the compression load shown by the above-mentioned relation curve is changed from the displacement amount (x) = 0 (mm) to the displacement amount (x) = 30. (Mm)
The area value obtained by integrating up to (black-painted portion in FIG. 1) was taken as the energy absorption amount.

[0035]

[Table 2]

As is clear from the results shown in Table 2, the foam for filling a structure according to the present invention has an excellent compression rigidity and a very large energy absorption amount. On the other hand, the foams obtained from the foamable composition of Comparative Example also have a small compression rigidity, a small energy absorption amount, the structure-filling foamable rubber composition and the structure-filling foam according to the present invention. The superiority was revealed.

[0037]

As is apparent from the above description, according to the foamable rubber composition for filling a structure according to the present invention, cost can be advantageously reduced, and excellent storage stability can be obtained. is there. And, since the foamable rubber composition has excellent storage stability as described above, its handling becomes very easy.

Further, the foamable rubber composition for filling a structure according to the present invention has excellent storage stability, so that when a structure is filled with the foamable rubber composition, a conventional epoxy resin foaming composition is used. As described above, the reaction does not automatically proceed before heating and the foaming does not become insufficient.

Further, in the foam for filling the structure according to the present invention, the compression rigidity thereof is 0.5 k per 25 cm ² .
Since it has N / mm and the energy absorption amount is 100 kN · mm or more per 25 cm ² , it has high rigidity and can absorb a large impact. When applied to automobiles, it can effectively improve the safety of passengers.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between a displacement amount and a compressive load when a structure-filling foam according to the present invention is compressed.

Claims (4)

[Claims] 1. A foamable rubber composition which is placed in a predetermined void in a structure and is foamed by being heated to fill the void in the structure, wherein the amount of diene rubber is 100 parts by weight. In contrast, 10 to 50 parts by weight of sulfur and 5
A foamable rubber composition for filling a structure, characterized by comprising -40 parts by weight of a foaming agent. 2. A foamable rubber composition which is placed in a predetermined void in a structure and is foamed by being heated to fill the void in the structure, which is added to 100 parts by weight of a diene rubber. In contrast, 1 to 30 parts by weight of sulfur, 5 to 1
A foamable rubber composition for filling a structure, which comprises 100 parts by weight of a rigidity-imparting agent and 5 to 40 parts by weight of a foaming agent. 3. With respect to 100 parts by weight of diene rubber,
A compressive rigidity of 0.5 kN / mm per 25 cm ² was obtained by heating and foaming a foamable rubber composition containing 10 to 50 parts by weight of sulfur and 5 to 40 parts by weight of a foaming agent.
It is above, and the energy absorption amount is 100 kN · mm or more per 25 cm ² , and the foam for structure filling is characterized. 4. For 100 parts by weight of diene rubber,
A foaming rubber composition obtained by blending 1 to 30 parts by weight of sulfur, 5 to 100 parts by weight of a rigidity-imparting agent, and 5 to 40 parts by weight of a foaming agent is heated and foamed to obtain a compression rigidity of 25.
cm is ² per 0.5 kN / mm or more, and the structure filling foam energy absorption amount is equal to or is 25 cm ² per 100 kN · mm or more.